"use strict"; // selecting class const _ = c => document.getElementsByClassName(c); // selecting id const __ = id => document.getElementById(id); // common factor function cf(a, b) { let r = a % b; return r === 0 ? Math.abs(b): cf(b, r); } // for evaluation of value function evaluate(val) { let v = eval(val); return v === Math.floor(v) ? v: val; } // for precise answer function exact(i, val) { _("values")[i].innerHTML = Number(eval(val).toFixed(2)); } // vibration feedback const vib = () => navigator.vibrate(100); let signs = ['+', '-']; function isOperator(n, i) { n = n[0]; _("operators")[i].value = n; for (let sign of signs) { if (n == sign) { _("operators")[i].value = n; break; } else { _("operators")[i].value = ""; } } } /* If the equation cannot be solved by splitting the middle term, quadratic formula will be used */ function byFormula(a, b, c, d) { if (d === 0) { let val = (-b) / (2 * a); __("res").innerHTML += "
Since discriminant is 0, both values of x are equal.
x = " + val; } else { let val1 = (-b + Math.sqrt(d)) / (2 * a); let val2 = (-b - Math.sqrt(d)) / (2 * a); __("res").innerHTML += "
First value of x = " + val1.toFixed(4); __("res").innerHTML += "
Second value of x = " + val2.toFixed(2); } } function solve(a, b, c, m, n, o) { vib(); __("solution").style.display = "block"; __("res").innerHTML = ""; if (a === 0) { __("res").innerHTML = "Incorrect quadratic equation."; return; } a = (m != "-") ? a: -a; b = (n != "-") ? b: -b; c = (o != "-") ? c: -c; m = (m == "+") ? "": m; n = (n == "-") ? "": "+"; if (b === 0 && n === "") n = "-"; o = (o == "-") ? "": "+"; if (c === 0 && o === "") o = "-"; // equation let eq = `${a}x² ${n} ${b}x ${o} ${c} = 0`; __("res").innerHTML += eq + "
"; // discriminant const d = (b * b) - (4 * a * c); if (d < 0) { __("res").innerHTML += "
Since discriminant is less than 0, real roots are not possible for this equation."; return; } // product let p = a * c; // for factors let arr = []; for (let i = -p; i <= p; i++) { if (p % i === 0) arr.push(i); } // middle term split let nums = []; outer: for (let el1 of arr) { for (let el2 of arr) { if (b < 0) { if (el1 + el2 === b && el1 * el2 === p && (el1 < 0 || el2 < 0)) { nums.push(el1, signs[0], el2); break outer; } } else { if (el1 + el2 === b && el1 * el2 === p) { nums.push(el1, signs[0], el2); break outer; } } } } // removing sign when -ve if (nums[0] < 0 || nums[2] < 0) nums[1] = ""; if (nums.length === 0) { __("res").innerHTML += "This equation can\'t be solved by splitting the middle term.
But the roots can be found by the quadratic formula.
"; byFormula(a, b, c, d); return; } let middle = a + "x² " + n + " " + nums[0] + "x " + nums[1] + " " + nums[2] + "x " + o + " " + c + " = 0
"; __("res").innerHTML += middle; let n1 = cf(Math.max(a, nums[0]), Math.min(a, nums[0])); n1 = (a < 0) ? -n1: n1; let n2 = cf(Math.max(nums[2], c), Math.min(nums[2], c)); n2 = (b < 0) ? -n2: n2; /* n1x(r1x + r2) + n2(r3x + r4) where, r1 = r3 r2 = r4 */ let r1 = Math.floor(a / n1); let r2 = Math.floor(nums[0] / n1); let r3 = Math.floor(nums[2] / n2); let r4 = Math.floor(c / n2); // signs let s1 = (r2 < 0) ? "": "+ "; let s2 = (n2 < 0) ? "": "+ "; let s3 = (r4 < 0) ? "": "+ "; __("res").innerHTML += `${n1}x(${r1}x ${s1}${r2}) ${s2}${n2}(${r3}x ${s3}${r4}) = 0
`; // common let c1 = `(${n1}x ${s2} ${n2})`; let c2 = `(${r1}x ${s3} ${r2})`; // (n1x + n2) + (r1x + r2) = 0 __("res").innerHTML += `${c1}${c2} = 0
`; if (n1 < 0) { n1 *= -1; n2 *= -1; } if (r1 < 0) { r1 *= -1; r2 *= -1; } let val1 = evaluate(-n2 + "/" + n1); let val2 = evaluate(-r2 + "/" + r1); __("res").innerHTML += "
Value 1 of x = " + val1 + ""; __("res").innerHTML += "
Value 2 of x = " + val2 + ""; let vals = [val1, val2]; for (let i = 0; i < 2; i++) { _("values")[i].onclick = () => { exact(i, vals[i]); vib(); } } } window.onload = function () { const inputs = document.querySelectorAll("input") .forEach(input => (input.onclick = () => input.value = "")); };

Ouadratic Equation Solver - Splitting the Middle Term